Depression diagnosis, according to the Diagnostic and Statistical Manual of Mental Disorders-5 (DSM-5), hinges on the presence of at least five symptoms, with either depressed mood or anhedonia being mandatory. While these symptoms can be broadly categorized into somatic and non-somatic groups, the DSM-5 traditionally approaches depression as a binary condition—present or absent. However, depression exists on a spectrum of severity, often measured using scales like the Hamilton Depression Rating Scale (HAMD). A prior study highlighted that individuals with moderate depression (MD) showed greater cardiac-autonomic modulation impairments compared to those with severe depression (SD). Despite these findings, clinical practice often relies less on scales.
This analysis aims to determine if DSM-5 symptoms can effectively differentiate between SD and MD, and MD from non-depressed (ND) individuals. The research utilized the Structured Clinical Interview for DSM-5® Disorders for diagnosis and the HAMD to assess severity. Depression severity classifications (MD and SD) were based on HAMD scores in diagnosed individuals, while the ND group met neither DSM-5 depression criteria nor HAMD score thresholds. From a pool of 782 outpatients, 46 were identified with SD. MD and ND subjects were then randomly selected, matching the demographic profile of the SD group for comparative analysis.
The results of discriminant analysis revealed that depressed mood is the most significant symptom distinguishing ND from MD individuals. Conversely, anhedonia emerged as the key differentiator between SD and MD. Among the secondary DSM-5 criteria, somatic symptoms were more prominent in differentiating ND from MD, while non-somatic symptoms were more effective in distinguishing SD from MD patients.
The prominence of somatic symptoms in MD may suggest reduced vagal tone or heightened sympathetic activity, potentially increasing cardiovascular risk. Conversely, the association of non-somatic symptoms with SD indicates a higher risk of suicide in these patients. Identifying the dominant symptom cluster in a patient can inform more tailored pharmacological interventions. This approach could help avoid prescribing antidepressants that might unnecessarily elevate cardiac risk in MD patients. When non-somatic symptom clusters suggest SD, the treatment strategy should prioritize suicide prevention.
In conclusion, depression severity can be inferred from the DSM-5 criteria. The combination of anhedonia and non-somatic symptoms points towards severe depression. Conversely, depressed mood coupled with somatic symptoms is more indicative of moderate depression. These findings suggest that DSM-5 symptom presentation can offer valuable insights into depression severity and guide more targeted treatment strategies.
